Do you know how to handle the top 10 motor faults? (1)
Generator overheating
(1) The generator did not operate according to the technical conditions of a constant force motor, such as high stator voltage and increased iron loss; Excessive load current leads to increased copper loss in the stator winding; The frequency is too low, which slows down the speed of the cooling fan and affects the heat dissipation of the generator; The power factor is too low, which increases the excitation current of the rotor and causes the rotor to heat up. Check whether the indication of the monitoring instrument is normal. If it is abnormal, necessary adjustments and treatments should be made to ensure that the generator operates according to the specified technical conditions.
(2) The three-phase load current of the generator is unbalanced, and the overloaded one phase winding will overheat; If the difference in three-phase current exceeds 10% of the rated current, it is considered a serious imbalance of three-phase current. The imbalance of three-phase current will generate a negative sequence magnetic field, thereby increasing losses and causing heating of components such as magnetic pole windings and bushings. The three-phase load should be adjusted to maintain the balance of the currents in each phase as much as possible.
(3) The air duct is blocked by dust accumulation, resulting in poor ventilation and difficulty in dissipating heat from the generator. Dust and oil stains should be removed from the air duct to ensure unobstructed flow.
(4) The inlet air temperature is too high or the inlet water temperature is too high, and the cooler is blocked. The inlet air or water temperature should be lowered to remove blockages inside the cooler. Before the fault is resolved, the generator load should be limited to reduce the generator temperature.
(5) If there is too much or too little lubricating grease added to the bearing, lubricating grease should be added according to regulations, usually 1/2~1/3 of the bearing chamber (upper limit for low speed and lower limit for high speed), and it is advisable not to exceed 70% of the bearing chamber.
(6) Bearing wear. If the wear is not severe, it may cause local overheating of the bearing; If the wear is severe, it may cause friction between the stator and rotor, resulting in overheating of the stator and rotor. The bearings should be checked for noise. If friction is found between the stator and rotor, the machine should be stopped immediately for maintenance or bearing replacement.
(7) The insulation of the stator core is damaged, causing a short circuit between the pieces, resulting in increased eddy current loss and heating in the local area of the core. In severe cases, it can damage the stator winding. The machine should be stopped immediately for maintenance.
(8) The parallel wires of the stator winding break, causing the current of other wires to increase and generate heat. The machine should be stopped immediately for maintenance.
The neutral line of the generator has abnormal voltage to ground
(1) Under normal circumstances, low voltage caused by uneven air gap and magnetic potential under each magnetic pole due to the influence of high-order harmonics or manufacturing processes in constant force motors. If the voltage is between one to several volts, there is no danger and no need to deal with it.
(2) The generator winding has a short circuit or poor insulation to ground, which can lead to deterioration of electrical equipment and generator performance, and is prone to heating. It should be repaired in a timely manner to prevent the accident from escalating.
(3) When there is no voltage between the neutral line and the ground under no-load conditions, and when there is a load, voltage appears due to three-phase imbalance. The three-phase load should be adjusted to achieve basic balance.
Generator current too high
(1) The load is too heavy and should be reduced.
(2) If there is a phase to phase short circuit or grounding fault of the constant force motor in the transmission line, the line should be inspected and the fault can be resolved to restore normal operation.
Generator terminal voltage too high
(1) The voltage of the generator parallel to the power grid is too high, and the voltage of the parallel generator should be reduced.
(2) The malfunction of the excitation device causes overexcitation, and the excitation device should be repaired in a timely manner.
Insufficient power
Due to insufficient compensation from the excitation device voltage source of the Hengli motor, the excitation current required for armature reaction cannot be provided, resulting in the generator terminal voltage being lower than the grid voltage and unable to deliver rated reactive power. The following measures should be taken:
(1) Connect a three-phase voltage regulator between the generator and the excitation reactor to increase the generator terminal voltage and gradually increase the magnetic potential of the excitation device.
(2) By changing the phase between the excitation device voltage magnetic flux potential and the generator terminal voltage, the total synthesized magnetic flux potential can be increased. A resistor of several thousand ohms and 10W can be connected in parallel at both ends of each phase winding of the reactor.
(3) Reduce the resistance of the variable resistor to increase the excitation current of the generator.
